In May last year Timothy Garton Ash tweeted from China, “Wonderful to see Isaiah Berlin up there among ‘All Sages’ in Wangsheng bookstore here in Beijing.” Garton Ash attached a picture of a wall of framed photographs of leading modern thinkers from a Beijing bookshop with Berlin in the middle. Twelve days later the seventh Isaiah Berlin Memorial Lecture was given in Riga by Berlin’s longtime editor Henry Hardy to a packed hall. Previous speakers in Riga have included Ian Buruma, Michael Ignatieff, John Gray and Anne Applebaum. On October 2, a party was held at Wolfson College, Oxford, to celebrate the publication of the fourth and final volume of Berlin’s Letters.

From Oxford to Beijing and Riga Isaiah Berlin still matters. Nowhere do his ideas matter more than where they are under threat. And as the threats grow, in China and Putin’s Russia, in Ukraine, Eastern Europe and throughout the Muslim world, his influence resonates in recent writings on multiculturalism and on the fragility of liberalism and democracy by a number of leading political essayists and thinkers on both sides of the Atlantic.

This might seem obvious. Berlin was perhaps the greatest liberal political thinker of the postwar period so, of course, his ideas should matter today. But his career and influence were less straightforward than one might think. Berlin was a fascinating barometer of his times. The rise and fall of his reputation tell us a great deal about the cultural and political changes of the past 60 years.

Before 1950 Berlin was little known outside Oxford and the East Coast of America where he had made his name during the war serving the British government. He had published one book, on Karl Marx (1939), which received two reviews, and a few articles on philosophy.

Berlin’s career took off in the 1950s and early ’60s. He was professor of Social and Political Theory at Oxford (1957-66) and gave a famous inaugural lecture, published as Two Concepts of Liberty (1958). He was a popular lecturer in America and gave a number of prestigious public lectures in Britain. He published perhaps his most famous work, The Hedgehog and the Fox, in 1954 and established his reputation as a political thinker with his critiques of historical determinism and his seminal writings on liberty. He also became a household name, as a broadcaster on the BBC’s Third Programme and Home Service and as a reviewer and essayist for prestigious journals in Britain and America. He watched the Coronation of the Queen for the Daily Telegraph in Piccadilly and was photographed by Cecil Beaton, he met Picasso, Shostakovich and Stravinsky, and was invited to 10 Downing Street and the Kennedy White House.

However, Berlin then came under attack from the New Left and later the New Right from the late 1960s to the ’80s. Between the mid-Fifties and the late 1970s he published Four Essays on Liberty and Vico and Herder, two books in almost a quarter of a century. After retiring as Chichele professor at Oxford in 1967 he went into a kind of semi-retirement. His 1970 essay on Turgenev was his last work on Russian intellectual history. Crucially, he was not interested in ’60s issues: the wars of liberation in the post-colonial world, feminism, gay rights, the New Left. A new generation of historians of political thought — Pocock, Quentin Skinner, John Dunn — did not seem to engage much with his work. Years later, in 1998, Dunn’s review of Berlin’s biography was entitled “For Services to Conversation”. In 1987, Daniel Dennett’s The Philosophical Lexicon had this entry on Berlin: “berlin, N. An old-fashioned stage coach, filled with international travellers, all talking rapidly and telling anecdotes of vivid life elsewhere. ‘As the berlin came through town, one could hear many accents one had never heard before, and delightful tales’.”

Berlin felt an increasingly embattled figure. In 1968 he wrote to a friend: “I feel depressed by the rapid growth of barbarism.” The next month he wrote of “the bearded students — who are now, in point of fact, swarming through Oxford, attacking All Souls, putting up obscene graffiti on the walls”.

Two things then dramatically changed the way Berlin was perceived. First, Henry Hardy brought together a number of previously unpublished essays and lectures in a series of books. For years Berlin was thought of as a brilliant speaker and lecturer who had produced remarkably few books. In the words of his close friend, Maurice Bowra, “Though like Our Lord and Socrates he does not publish much, he thinks and says a great deal and has had an enormous influence on our times.” However, from Russian Thinkers and Concepts and Categories, both published in 1978, eight new collections of essays were brought out before Berlin’s death in 1997. He was no longer thought of as simply a brilliant writer on liberalism, but also a fascinating writer on the enemies of liberalism and the Enlightenment; on Russian thought and literature from Herzen and Turgenev to Akhmatova and Pasternak; on Romanticism; and on human nature, pluralism and “the sense of reality”.

As these new books poured out, Berlin’s ideas acquired a new relevance. The fall of the Berlin Wall and the collapse of Soviet Communism added to the reputation of longtime critics of Communism, like Berlin and the historian Robert Conquest. To put it simply, they had got the central question of post-war Western politics right. Communists like Eric Hobsbawm, pro-Soviet historians like E.H. Carr, had not. Liberalism and pluralism had won.

However, what made Berlin’s ideas so interesting was not just the triumph of liberalism in the Cold War but the return of old ghosts to Europe: nationalism, ethnic hatreds and anti-Semitism. At the same time, the rise of militant Islam, the emergence of a new intolerance symbolised by the fatwa against Salman Rushdie and the increasing complexities and contradictions of multiculturalism, made Berlin’s ideas seem more relevant than ever. Within a few years of the fall of Soviet Communism, new enemies of liberalism and pluralism had emerged: religious fundamentalism, especially militant Islam, and irrationalism. Berlin’s emphasis on the clash of values and on the difficulties of choice between rival ideas and values appealed to an influential generation of political writers.

Berlin’s new influence took various forms: three programmes on BBC2 in the 1990s, major tributes to Berlin following his death in 1997, a biography by Michael Ignatieff (1998) and a scholarly edition of his letters (2004-15). Just as important, however, was Berlin’s influence on political thinkers, During the 1990s there were major essays on his ideas by John Gray, Steven Lukes, Michael Walzer, Alan Ryan, Judith Shklar and Ronald Dworkin, among others.

However, it is really in the last few years that Berlin’s impact on a group of interesting political writers on both sides of the Atlantic can be seen. These are Berlin’s children. The key figures in this group include Michael Ignatieff and John Gray; the essayists and writers Ian Buruma and Timothy Garton Ash; and the historian of ideas Mark Lilla, professor of humanities at Columbia University.

Clearly, there are significant differences between them, of background, personality and core interests. Buruma, for example, is drawn to China and 20th-century Japan in his writing. Ignatieff had a brief career in Canadian politics. Garton Ash made his reputation as a writer on the 1989 revolutions against Soviet Communism. Gray is altogether a more speculative, wide-ranging thinker, with a dark dystopian tone and wide literary interests, from J.G. Ballard to T.F. Powys.

However, there are also interesting links between them all. They are all British or North American (Buruma was born in the Netherlands but teaches in the United States and much of his writing is for American publications) and except for Hardy have often moved between Britain and America. All were born just after the war and came of age in the 1970s, when Berlin’s liberalism was least in fashion. None are straightforwardly on the Left or Right. For years there was an alliance of political writers and thinkers formed by Vietnam and anti-colonial struggle. This alliance broke apart in the 1990s and 2000s over reactions to the fatwa against Rushdie, Kosovo, 9/11, and above all, intervention in Iraq. Many, like Edward Said, Noam Chomsky, John Pilger and the writers around the New Left Review went one way. The Berlin-influenced group of writers (and one could add Christopher Hitchens, an outspoken critic of Berlin) went the other.

All of them, like Berlin, are intellectuals who move between the university and what one might call higher journalism. All of them have taught, or teach, at prestigious universities in Britain or America, but most have interesting cultural interests. Ignatieff has written novels and screenplays. Buruma’s book Theater of Cruelty includes essays on Fassbinder, Clint Eastwood and Leni Riefenstahl.

There are two other interesting links. All are contributors to the New York Review of Books, edited by Berlin’s close friend Robert Silvers. That perhaps defines their political position better than anything else, a kind of New York Review liberalism, humane, thoughtful, literary and political. The other link is geographic. They are largely linked by Berlin’s world of Oxford, London, the East Coast and Israel. It is worth noting that these are not just places where Berlin most felt at home and which most mattered to him (the Russia he loved was in the past), but where his ideas most resonate today. There were memorial services in each of these places for him when he died in 1997.

Above all, what Berlin’s children share is a sense of standing up for liberalism, pluralism and humanitarianism when these values are under attack across our world. In 2009 Michael Ignatieff gave a lecture called “Liberal Values in Tough Times”. That pretty much sums up these writers’ sense of the world. They have no doubt that these are dark times and emphasise the fragility of democracy and liberalism against its new enemies. None are easy optimists or triumphalists. They have inherited Berlin’s “agonistic liberalism” (to use the title of an essay by Gray).

This dark side to their writing reflects our times: genocide, refugees, religious and ethnic persecution, intolerance. These are writers who are prepared to speak of evil as a crucial feature of our world. Last September, Michael Ignatieff wrote an essay on “The New World Disorder” for the New York Review of Books. He began with Putin’s annexation of Crimea and the shooting down of flight MH17 over Ukraine. He went on to look at a world of violence and disorder, from Ukraine to IS, from Gaza to tensions between Japan and China in East Asia. At the centre of these conflicts he saw “the dual challenge of the new authoritarianism and the new extremism”. There is little room for optimism in such a vision.

In recent years this group of writers has taken a darker view of the fragility of the world order and of democracy and liberalism, faced with powerful new enemies: Russian and Chinese authoritarianism, failed states in Africa and the Middle East and Islamic fundamentalism. This has given their writings a shared tone, a dark pessimistic mood very different from the triumphalism of many post-1989 writers.

This darkness also reflects an aspect of Berlin’s own thought, the refusal to believe in easy solutions. In the 2013 revised edition of his book Isaiah Berlin: An Interpretation of his Thought (Yale, £18.95), John Gray writes, “The cornerstone of his thought is his rejection of monism in ethics — his insistence that fundamental human values are many, that they are often in conflict and rarely, if ever, necessarily harmonious, and that some at least of these conflicts are among incommensurables — conflicts among values for which there is no single, common standard of measurement or arbitration.” But he goes on to say that Berlin’s “subversive originality” lies in “an agonistic liberalism, a liberalism of conflict and unavoidable loss among rivalrous goods and evils”.

This is what links Berlin’s children: how they bring Berlin’s ideas to bear in their writing about the world’s crises today. In 2012, Michael Ignatieff gave the Isaiah Berlin Memorial Lecture in Riga, “Isaiah Berlin, the Soviet Union and the Captive Nations”. Significantly, he began with a quotation from Cavafy’s poem, “Waiting for the Barbarians”. The barbarians of old were the Soviet Communists. But what of the new barbarians, Putin’s Russia and the new China? Ignatieff spoke of “the front line of liberal democracy’s decisive new encounter — no longer with totalitarianism of the Left or the Right, which defined liberalism throughout the 20th century, but now with new regimes that have no historical precedent, post-Communist oligarchies — Russia and China”. He continued: “Russia and China are attempting to demonstrate a novel proposition: that economic freedoms can be severed from political and civil freedom, and that freedom is divisible. The liberal democratic creed is that freedom is indivisible . . . China and Russia both pose a strategic challenge to this belief, and the shape of the 21st century will be determined by who is right.”

At this point Ignatieff invoked Berlin and looked to the lessons that his Cold War liberalism can teach us still. For him, Berlin offers “humility about history, firmness to stand against wrong and the openness to engage and learn from those we oppose. Berlin incarnated this temperament, and living within its disciplines would stand us in good stead as we face challenges from new forms of oppression that he never lived to see.”

That same summer John Gray gave a talk for Radio 4 on “The Trouble with Freedom”. It began with a small boy watching a mob lynch a terrified man in Petrograd in 1917. The boy was Isaiah Berlin. Berlin often told the story as a parable of revolutionary violence. But Gray read it differently. “Not long after the start of the 21st century,” he said, “we like to tell ourselves an uplifting story in which freedom expands whenever tyranny is overthrown. We believe that freedom and democracy are inseparable, so that when a dictator is toppled the result is not only a more accountable type of government but also greater liberty throughout society.” However, Gray went on, it’s not just tyrants who prevent freedom but also “failed and enfeebled states”, from Mexico to Iraq. Gray’s conclusion was sobering: “The overthrow of tyranny doesn’t by itself expand liberty.” Berlin understood “that liberty is a fragile achievement that can be undermined in many different ways.”

This is an argument Gray resumed in an essay called “The Liberal Delusion” (Prospect, October 2014), written on the 25th anniversary of the fall of the Berlin Wall. Again, he turned to Berlin’s ideas, this time as part of a longer liberal tradition, which “recognised that democracy does not necessarily protect freedom. The greatest danger for these liberals was not that the historical movement towards democracy would be reversed, but rather the ascendancy of an illiberal type of democracy . . . Most human beings in every society, much of the time, care about other things more than they care about being free.”

This concern about the dark side of democracy is at the heart of Gray’s Isaiah Berlin Memorial Lecture in 2013 on “Isaiah Berlin and the Meaning of Freedom”. Gray began his lecture in Riga arguing that “we have a great deal to learn from Berlin’s thinking today, Sometimes the lessons are uncomfortable. Sometimes they may strike people as disillusioning.” He defined Berlin’s liberalism as both stoical, “in that it accepts that the pursuit of freedom always involves losses,” and sceptical, “in that it accepts that there are many moral and political dilemmas to which there is no right solution, which are not politically soluble.”

At the heart of Berlin’s scepticism, argued Gray, is that there are many things which freedom is not: “Freedom is not happiness, it is not justice, it is not democracy.” There can be illiberal democracies, which not only do not promote freedom, but are even hostile to it. Our world is full of elected governments which don’t respect the freedom of individuals or minorities, or liberal values. What Gray learned from Berlin is that it is naive to believe that all that is needed to promote freedom is to eliminate tyrants. The removal of tyrants in the Arab Spring led to anarchy and failed states from Iraq to Libya. In post-Communist Russia it led to a new mix of illiberal democracy, authoritarianism and surviving elements of the old Soviet regime. Democracy, argued Gray, is a good thing but it is not the same thing as freedom.

Gray looked at various ways in which freedom is under threat today. He identified three main threats to freedom. First, for many years free societies were more prosperous than unfree ones. The West was freer and richer than the Soviet Union, China or Cuba. But today authoritarian regimes like China are no longer more economically backward and, indeed, large parts of Europe, especially on the periphery, are stagnant and shrinking.

The political consequences of economic stagnation, Gray goes on, are dangerous to freedom. “The old demons of 20th century Europe — anti-Semitism, the hatred of the Roma and homosexuals — are on the march again.” Democracy may not give way to 1930s fascism, but it may be poisoned or deformed by illiberalism.

Another threat to freedom comes from illiberal democracies. In the Islamic world tyrants have given way to failed states and popular theocracies. This brings us back to Berlin. He learned from J.S. Mill, de Tocqueville and Benjamin Constant, all supporters of democracy, that there were dangers in illiberal democracies. In today’s world we see these dangers on the move: women and homosexuals live in fear, Christian and Jewish minorities are persecuted.

Isaiah Berlin often criticised determinists who said they were on the right side of history. In October 1997 President Clinton told China’s President Jiang Zemin that he was “on the wrong side of history”. In March 2014 Obama told Putin he was “on the wrong side of history”. Now we are less sure who is on the right side of history. We are less comfortable with the very notion of the triumph of Western ideas and values. We look today at the enemies of liberalism — Putin’s Russia, China and fundamentalist Islam — at failed states, economic fragility and terrorists and wonder whether pessimism, not optimism, is the order of the day.

Writers like Gray, Garton Ash and Ignatieff speak to us today because they believe that this is a time for scepticism and stoicism, not triumphalism. From Riga to Beijing, this is a lesson they have learned from a Jewish refugee who fled revolutionary Russia and whose relatives were slaughtered in Nazi-occupied Latvia.